The primary purpose of the study is to compare clinical response rates (excellent or good) of MK-0966 to Nambumetone in the treatment of osteoarthritis of the knee over a 6 week period. The study is designed as a randomized, double-blinded placebo controlled study. Eligible patients will be randomized to one of three treatment groups and will receive either MK-0966 12.5 mg, Nambumetone 10000mg, or placebo, following an NSAIDA washout period. Clinical safety and efficacy data will be collected at 2,4 and 6 weeks of therapy.